1. Field of the Invention
The present invention relates to an apparatus and a method for detecting an ovulation period of mammals such as hogs, cows, and men.
2. Background Art
Conventionally, ovulation period detecting apparatuses for mammals to be used for predicting the timings of semen deposition include those proposed in Japanese Patent Laid-open Publications Nos.Hei 7-38856, 7-87837, 7-87838, 7-87840, 7-87841, and 7-87842, for example, in which the sodium ion concentration on vaginal mucous membrane is measured on the basis of impedance in inverse proportion thereto to detect the timing of the ovulation period, thereby determining an insemination period or a contraception period.
More specifically, in the case of mammals, e.g., hogs, the equivalent impedance on the vaginal mucous membrane in a non-ovulation period presents such a stable curve as shown in FIG. 9, in which it varies periodically between a zero point and 1.0 k .OMEGA. as time elapses, assuming the equivalent impedance of blood as the zero point. The equivalent impedance starts increasing from 42 to 38 hours before ovulation, approaches the equivalent impedance of water infinitely, becomes generally the same as the equivalent impedance of water just before ovulation, and then decreases sharply to a minimum in two to three hours. Accordingly, the conception ratio of insemination is greatly improved by accurately obtaining the equivalent impedance in insemination-appointed mammals and by depositing of preserved semen at appropriate timings selected for the type of the preserved semen.
However, it is hard to actually obtain fine impedance data, as shown in FIG. 9, in daily routines at a ranch. That is, since the impedance is measured in such a condition that a plurality of electrodes provided on the extremity of a bar-shaped detecting unit are pressed against the vagina and a voltage is applied to the electrodes, the lack or unstableness of a force for pressing the electrodes against the vagina causes the possible intervening of urine, inflammatory exudate, air, mucus, and the like between the electrodes and the vaginal mucous membrane, which gives rise to a problem in that exact and precise data can not be obtained. Therefore, the accurate measurement of the impedance on the vaginal mucous membrane is need.
Besides, the impedance is measured in every mating season on every objective mammal at regular intervals, e.g., a few hours from approximately 40 hours before ovulation, to store data with a time-variation as shown in FIG. 9, for the reason that the timing of ovulation period is predicted and determined on the basis of the stored data. Accordingly, the amount of data on respective objective mammals becomes enormous, which gives rise to a problem in that the data collection is hand- and time-binding as well as burdensome and labor-requiring.